Preeclampsia (PE) remains one of the leading causes of maternal and neonatal morbidity and mortality throughout the world. Perinatal mortality is increased 5-fold in pregnancies complicated by PE. Nearly 15% of preterm births occur secondary to early onset of the disease. Despite extensive research efforts, no reliable methods are currently available for the prediction and prevention of PE. The accurate and early prediction of patients at risk would allow more intensive monitoring and improved testing for possible preventative measures. Any advance in the prevention or treatment of PE could result in significant improvement in maternal mortality, in reduced perinatal morbidity and in reduced healthcare costs. Numerous clinical and biochemical tests have been proposed for the early detection of PE. However, the realization of this goal has been hindered by the fact that PE constitutes a heterogeneous condition likely to result from multiple etiologies. Evaluation of biologic samples by chromatographic separation followed by mass spectrometric evaluation, one which resolves proteins by mass, can provide an inventory of the peptides and proteins present at any given time. This novel technology, a proteomic approach, will be applied for the first time to the evaluation of PE. Previous studies have successfully used this approach to evaluate and identify patients afflicted with early ovarian, breast and prostate cancers. Based on those studies and our own preliminary work, we hypothesize that a proteomic pattern exists within maternal serum, at an early gestational age, one that will accurately predict the subsequent onset of PE. We further propose that proteomics may be used to define and characterize the differences between subtypes of PE including HELLP syndrome, severe preeclampsia and mild preeclampsia. Additionally, we hypothesize that a unique circulating proteomic pattern of PE, one identified in early second trimester, will afford new insights into the underlying pathophysiology responsible for the development of PE. [unreadable] [unreadable]